As well known in the art, a very high-data rate backbone network for optical communication employs an active component, e.g., a high-quality laser diode (LD)/photo diode (PD), an optical switch, a high-speed router, a DWDM (Dense Wavelength Division Multiplexing) device, a cross connect device or the like. Meanwhile, it is important for a subscriber network in great demand to employ efficient, simply manufacturable, solid and low-priced components. Especially, an efficient optical coupling of an optical device, e.g., a laser, is indispensable for an optical performance. As for various methods for achieving a enhanced butt coupling efficiency by way of matching modal profiles between the optical device and the optical fiber, there have been suggested a optical coupling via a passive optical device such as micro-lenses or fiber tips and a direct coupling method. However, in the optical coupling method using micro-lenses, an optical axis alignment between the micro-lenses and the optical fibers needs to be performed within a submicron level and, further, a high cost is required for a specific apparatus or the like to assembly them. As for the fiber tip, a lensed fiber or a tapered fiber is used. In such case, an appropriate working distance is required between the micro-lenses and the optical devices, which lengthens a front end of the optical fiber.
As for related information, there is a report on “Development of TEC lensed ribbon fiber for optical devices packaging”, published by Electronics and Telecommunications Research Institute, Korea, Nov. 11, 2003.